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  <meta name="Generator" content="EditPlus®">
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<script>
	//负性值：false null NaN undefined '' 0
	//扔 扔 扔
	console.log(null && 2); //null
	console.log('哈哈' && undefined); //undefined

	console.log(12 || 13); //12
	console.log(0 || 13); //13

	console.log('3' == 3); //  parseInt(3abc)  强制 => 3
</script>